Apparatus for taking pictures of the images produced by electron optic apparatus



73 I Aw 39 o MULLER APPARATUS FUR TAKING PICTURES OF THE IMAGES PROBE GED BY THE ELECTRON OPTIC A?PARI\TUS Filed Jan. 28, 1941 INVENTOR Hsuvz Orro 11401.:

M Mm mu ME Jul/Tran ATTORNEY.

Patented Aug. 14, 1945 APPARATUS FOR TAKING PICTURES OF THE IMAGES. PRODUCED BY ELECTRON OPTIC APPARATUS Heinz Otto Miiller, Berlin- Spandau, Germany; vvested in the Alien Property Custodian l 1 "Application January 28,1941, Serial N0. 376,310 I In Germany October 17, 1939 V r 3. Claims. (01. 2501-65) This invention relates to electron optical apparatus in which a beam of electron rays is caused to produce photographic images.

In such apparatus, particularly in electronic microscopes, devices are necessary for observing the image on a fluorescent screen and then exposing a photographic plate'to the electron rays. It is known to provide a fluorescent screen which may be removed from the path 'ofraysby rotation. When turned into th'e p'ath of the beam,

the screen shows the image'to be photographed and at the same time covers thephotographic plate; By turning the screen out'of the beam path, the photographic plate is exposed until the screen is moved back into its original position. This method has the disadvantage that the'photographic plate is not uniformlyexposed to'the electron beam. The parts of th -photographic plate whichlie. nearer the pivot of the screen are exposed for a shorter time as compared with the other areas of the plate. Furthermore, it is not possible to adjust the exposure time with sufllcient accuracy, since the shutter is'" hand-operated. This is particularly disadvantageous when employing highly sensitive plates which require a short exposure time of accurate duration and uniform eifect. Furthermore, when effecting the response directly by moving the fluorescent screen away from the beam path, vibrations are apt to occur so that the sharpness of the" image may easily be impaired. v

It is an object of the inventionto illuminate the above-mentioned drawbacks of the known electron-optical apparatus and to provide means for exposing a photographic plate or the like to an image-producing electron beam while obtaining a uniform exposure of adjustable duration which is not afiected by the movement of the fluorescent screen necessary for observing and focusing the image preparatory to the exposure.

According to the invention a separate shutter is arranged within the vacuum vessel in the path of the electron beam between the screen and the photographic means. This shutter is of the adjustable type topermit selecting the exposure time. The actuating means for setting the shutter extend through the vacuum wall of the electronic vessel andare operable from the outside. In this manner it is possible to uniformly expose the entire surface of the photographic plate to the electron rays for an accurately adjusted period. This permits using highly sensitive plates with the additional advantage that the sharpness of the image is improved owing to the shorter exposure time. In the apparatus according to the invention, a focal plan shutter or a central metal shutter maybe used; In order to release the shutter, a mechanism is employed to advantage which is actuated with the'aidof the fluorescent screen. The releasing device is, for instance, so controlled by the fluorescent screen that the release is effected automatically after the screen has been moved away from the beam t .v I The accompanying drawing illustrates two embodiments of the invention in'diagrammatic form; 1 is a top view of afocal plane'shutter and its actuatingmeans; y 4

Fig. 2 is an axialsectionthrough an electronic microscope containing the shutter; and

Fig; 3 is a front view of the control'knobs a the shutter. I v

' Referring to the drawing, l denotes the vacuum wall of an electronic microscope, 2 is aphotoe' graphic plate, 3 a focal plane shutter. and 4 "a' fluorescent screen on which th irnageprbduced in. the microscope may be viewed before taking a pictur'e'thereof. The focal planeshutter' is of the type well known in photography." It contains a roller blind 23, provided with a'slot. 24. When inoperation, the blind moves along the plate so that the'slot and the. area" uncovered thereby'travel across theplate surface. The

v movement is effected by means of a spring (not shown). To wind up the spring; aknobj 5" is employed whose axis passes through the vacuum wall I withthejai'd of 'a sealingconelil iThe'ro ta'tionof knob '5 istransmitted to'the' shaft 9 "of the slit shutter through the gears l and 8. To

prevent the shutter from operating after its spring has been wound up, a pawl 10 is employed which cooperates with a ratchet wheel I l.

The release of the shutter is' efiected by means of the fluorescent screen 4 which may be rotated by means of a sealing cone not shown in Fig, 2 which is operated exteriorly of the vacuum vessel. In the end position shown in broken lines, the screen 4 presses against a stop 25 mounted on a lever l2 to which is secured the pawl H). A spring 13 pressing against the lever l2 holds the pawl l0 against the ratchet wheel II when winding up the shutter mechanism. When the screen 4 engages the stop 25 and displaces it against the action of the spring I3, the pawl H3 is moved out of engagement with the ratchet wheel I l and releases the shutter mechanism, thereby effecting an exposure of the photographic plate.

The exposure speed of a focal plane shutter depends on the width of the shutter slot and on the speed with which the slot moves across the wheel 8 serves to wind up the shutter, a second:

gear whel 14, independently rotatable aboutthe same shaft 9, is employed fonadjizstingzthezshutrter speed, for instance in the"last-mentioned'man'- ment. For adjusting the exposure time, the gear 1 is brought into engagementrwith-thesgears M. The displacement of the gear ls-isrefiectedi with the aid of a knob I5 whichdrives. a screw shaft I! carrying a screw nut 18. The latter: whena'cituated moves a forked lever IS in the'downward direction as indicated by an arrow, soitliat'cther gear. I slidablymounted onthe shaft 20 moves also in. the same: direction; untilitmeshesiwith the gear L41. In this positibnitheexposure' time may be: adiust'edby rotating, the knob 5.. To facilitate the adjustmentof the exposure timea pointer?! anda scale]! areprovidedas.illustratedin Fig. 3:.

Focal. plane shutters. which are provided with. asingle means for. both winding, up the" shutter spring and adjusting the exposure time are well' knownand anillustrative example is shown inth'e patent to Ki1ppenhend'er, No: 2',09U;390; patented. AugnshlZLlQBY;

As mentioned above, the release is effected'with the. aid. of.the fluorescent screen 4 within the vacuum device for, the. reception of" the. photographic material. Suchia releasaincontrastito theknown' devices, prevents an uneven'exposure of the phop tographic. plate as. is the. case. when the screenit self. formsthe shutter. Fiirthermore, the invention 'redncesthe effect of.vibratibns,,since the release ofl the. shutter. occurs only. after the. screen has passed. through. the first. portion. or. most? of its opening,movementiandrequiresmo manualop eration. throughsealihg cones or other devices apt tocause vibrationslof'the.veselwall; The. apparatus. according. to. the invention. may. be employed. in. electronic microscopes; mass spectrographslor. thelike.electronicapparatus. v Whatisclaimed'i's: V

L.An-. electron-optical. device for causingfan electron beam. to produce. photographic. images, comprisingavacuumvessel} a: photographic. means for receiving the. imagehai fluorescentscreen arrangedin. said vesselinfrontl ofTsaidTphotog-r'aphic controlled by said screen upon removal thereof from the electron beam path for releasing said shutten'so: as to the exposure of said photographiameanszf 2. An electron-optical device for causing an eleetmn: beams top'mduce' photographic images, comprising azvacuum vessel, a photographic means for receiving. theimage, a fluorescent screen arrangedii'n' said'vesseli'n front of said photographic means relative to the direction of the electron beam;.'sai'd screen being movable to permit being placed in .the path of the beam for observing. the image previoustothe; photographic exposure and to be removed from saidlpath preparatory-to the exposure, a focal planeshut'ter arrangedbetween said screen and said photographic mea'ns,. said. shutter having spring winding: means operable exteriorlyof saidvacuum' vessel"ancL a' mechanism for; releasing said spring winding means. and a stop arranged in the. patriot movement ofsaid' screen and connected with said'mecha'nism so. as to effect"a.rel'ease when said'screen reaches its in, operative position.

3.1A'n electron-optical device for causing. an electron. beam. to prodi ce' photographic images. comprisinga.vacuumyessella photographic means for receiving.v the image,.a.fi"uorescent' screen anrangedin saidvessel'in frontofsai'dlphotoeraphic means. relative, to the direction ofgthe; electron heam,. said screenbeing. rotatable about an axis parallel. to the. focal plane. of said photographic means to permit. beingplaced'inthe pathof'the Beam. for observing; the image previous tothe. photographic exposure. and to befturned' away from said. path. preparatory to the; exposure,, a. focal plane shutter 'arrangedbetween. said .screeri. and. said photographibimeans, saittshutt'en havihgi spring. winding; means. operable exteribrlyof'said vessel}. afv control;.mechani'sm..fbr releasing, saidspringwinding. means, andla stop di'sposed'so as .to. limit'the movement of saidlscreemwhn .the latter' is turned away from saidbeam path,,said. .stop.being. connected with. said. control" mechanism. to actuate. thel'att'er when-engaged by. saidlscreen- HEINZTO'ITIZU p l 

